Field of the Invention
The subject matter of this application relates to microelectronic packages and assemblies in which a plurality of semiconductor chips are stacked one above the other and electrically interconnected with a support element such as a package element or other circuit panel.
Description of the Related Art
Semiconductor die or chips are flat bodies with contacts disposed on the front surface that are connected to the internal electrical circuitry of the chip itself. Semiconductor chips are typically packaged with substrates to form microelectronic packages having terminals that are electrically connected to the chip contacts. The package may then be connected to test equipment to determine whether the packaged device conforms to a desired performance standard. Once tested, the package may be connected to a larger circuit, e.g., a circuit in an electronic product such as a computer, e.g., a server, among others.
Microelectronic packages can be fabricated which include semiconductor chips mounted on leadframes. Such packages can be incorporated in larger assemblies, typically as surface-mounted devices coupled to a circuit panel. In order to save space certain conventional designs have stacked multiple microelectronic elements or semiconductor chips within a package. This allows the package to occupy a surface area on a substrate that is less than the total surface area of the chips in the stack. However, conventional stacked packages have disadvantages of complexity, cost, thickness and testability.
In spite of the above advances, there remains a need for improved stacked packages and especially stacked chip packages which incorporate multiple chips for certain types of memory, e.g., flash memory. There is a need for such packages which are reliable, thin, testable, and that are economical to manufacture.